Device and method for fronthaul transmission in wireless communication system

ABSTRACT

A pre-5 th -Generation (5G) or 5G communication system for supporting higher data rates Beyond 4 th -Generation (4G) communication system such as Long Term Evolution (LTE) is provided. The device of a radio unit (RU) of a base station in a wireless communication system includes at least one transceiver and at least one processor coupled to the at least one transceiver, wherein the at least one processor is configured to receive a first control message including a section extension field from a digital unit (DU) via a fronthaul interface, identify additional information based on the section extension field, and acquire a beamforming weight based on the additional information, wherein the first control message is configured to schedule a terminal in a control plane.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser.No. 17/902,465 filed on Sep. 2, 2022; which is a continuationapplication of prior application Ser. No. 17/085,269 filed on Oct. 30,2020, which has issued as U.S. Pat. No. 11,477,801 on Oct. 18, 2022; andwhich is based on and claims priority under 35 U.S.C § 119(a) of aKorean patent application number 10-2019-0137034, filed on Oct. 30,2019, in the Korean Intellectual Property Office, the disclosure ofwhich is incorporated by reference herein in its entirety.

BACKGROUND 1. Field

The disclosure relates to a wireless communication system. Moreparticularly, the disclosure relates to a device and method forfronthaul transmission in a wireless communication system.

2. Description of Related Art

To meet the demand for wireless data traffic having increased sincedeployment of 4th generation (4G) communication systems, efforts havebeen made to develop an improved 5th generation (5G) or pre-5Gcommunication system. Therefore, the 5G or pre-5G communication systemis also called a ‘Beyond 4G Network’ or a ‘Post long term evolution(LTE) System’.

The 5G communication system is considered to be implemented in higherfrequency (millimeter (mm) Wave) bands, e.g., 60 gigahertz (GHz) bands,so as to accomplish higher data rates. To decrease propagation loss ofthe radio waves and increase the transmission distance, the beamforming,massive multiple-input multiple-output (MIMO), Full Dimensional MIMO(FD-MIMO), array antenna, an analog beam forming, large scale antennatechniques are discussed in 5G communication systems.

In addition, in 5G communication systems, development for system networkimprovement is under way based on advanced small cells, cloud RadioAccess Networks (RANs), ultra-dense networks, device-to-device (D2D)communication, wireless backhaul, moving network, cooperativecommunication, Coordinated Multi-Points (CoMP), reception-endinterference cancellation and the like.

In the 5G system, Hybrid frequency shift keying (FSK) and quadratureamplitude modulation (QAM) frequency quadrature amplitude modulation(FQAM) and sliding window superposition coding (SWSC) as an advancedcoding modulation (ACM), and filter bank multi carrier (FBMC),non-orthogonal multiple access (NOMA), and sparse code multiple access(SCMA) as an advanced access technology have been developed.

As transmission capacity increases in a wireless communication system, afunction split for functionally splitting a base station is applied.According to the function split, a base station may be split into adigital unit (DU) and a radio unit (RU), a fronthaul for communicationbetween the DU and the RU is defined, and transmission via the fronthaulis required.

The above information is presented as background information only toassist with an understanding of the disclosure. No determination hasbeen made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

SUMMARY

Aspects of the disclosure are to address at least the above-mentionedproblems and/or disadvantages and to provide at least the advantagesdescribed below. Accordingly, as aspect of the disclosure is to providea device and method for transmitting a control message on a fronthaulinterface.

Another aspect of the disclosure is to provide a device and method fortransmitting a management message on the fronthaul interface in thewireless communication system.

Another aspect of the disclosure is to provide a device and method fortransferring scheduling information along with other information on thefronthaul interface in the wireless communication system.

Another aspect of the disclosure is to provide a device and method fortransferring scheduling information along with, particularly, aregularization parameter on the fronthaul interface in the wirelesscommunication system.

Another aspect of the disclosure is to provide a device and method forreducing a memory burden of a radio unit (RU) due to storage of anormalization parameter, when operating a digital unit (DU) and the RUin the wireless communication system.

Another aspect of the disclosure is to provide a functional structure ofan RU for processing a normalization parameter in the wirelesscommunication system.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

In accordance with an aspect of the disclosure, an operation method of adigital unit (DU) of a base station in a wireless communication systemis provided. The operation method includes configuring a sectionextension field including additional information, and transmitting afirst control message including the section extension field to a radiounit (RU) via a fronthaul interface, wherein the first control messageis configured to schedule a terminal in a control plane.

In accordance with another aspect of the disclosure, an operation methodof a radio unit (RU) of a base station in a wireless communicationsystem is provided. The operation method includes receiving a firstcontrol message including a section extension field from a digital unit(DU) via a fronthaul interface, identifying additional information basedon the section extension field, and acquiring a beamforming weight basedon the additional information, wherein the first control message isconfigured to schedule a terminal in a control plane.

In accordance with another aspect of the disclosure, a device of adigital unit (DU) of a base station in a wireless communication systemis provided. The device includes at least one transceiver and at leastone processor coupled to the at least one transceiver, wherein the atleast one processor is configured to configure a section extension fieldincluding additional information, and transmit a first control messageincluding the section extension field to a radio unit (RU) via afronthaul interface, wherein the first control message is configured toschedule a terminal in a control plane.

In accordance with another aspect of the disclosure, a device of a radiounit (RU) of a base station in a wireless communication system isprovided. The device includes at least one transceiver and at least oneprocessor coupled to the at least one transceiver, wherein the at leastone processor is configured to receive a first control message includinga section extension field from a digital unit (DU) via a fronthaulinterface, identify additional information based on the sectionextension field, and acquire a beamforming weight based on theadditional information, wherein the first control message is configuredto schedule a terminal in a control plane.

A device and method according to various embodiments enables efficientoperations of interfaces of a digital unit (DU) and a radio unit (RU)via a control message and a management message.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1A illustrates a wireless communication system according to anembodiment of the disclosure;

FIG. 1B illustrates an example of a fronthaul structure according to afunction split of the base station according to an embodiment of thedisclosure;

FIG. 2 illustrates a configuration of a digital unit (DU) according toan embodiment of the disclosure;

FIG. 3 illustrates a configuration of a radio unit (RU) according to anembodiment of the disclosure;

FIG. 4 illustrates an example of a function split according to anembodiment of the disclosure;

FIG. 5A illustrates an example of a control message according to sectiontype 6 according to an embodiment of the disclosure;

FIG. 5B illustrates an example of a functional configuration of an RUfor beamforming information processing according to an embodiment of thedisclosure;

FIG. 5C illustrates a relationship between a regularization factor andscheduling according to an embodiment of the disclosure;

FIG. 6 illustrates an example of an extension field according to anembodiment of the disclosure;

FIG. 7 illustrates an example of a management message for section type 6according to an embodiment of the disclosure;

FIG. 8A illustrates an operation flow of a DU for an extension fieldaccording to an embodiment of the disclosure;

FIG. 8B illustrates an operation flow of an RU for an extension fieldaccording to an embodiment of the disclosure;

FIG. 9A illustrates an operation flow of a DU for a management messagefor section type 6 according to an embodiment of the disclosure;

FIG. 9B illustrates an operation flow of an RU for a management messagefor section type 6 according to an embodiment of the disclosure;

FIG. 10 illustrates an example of a functional configuration of an RUfor beamforming information processing according to an embodiment of thedisclosure;

FIG. 11 illustrates a relationship between a regularization factor andscheduling according to an embodiment of the disclosure; and

FIG. 12 illustrates an example of a relationship between DUs and RUs viaa section extension field according to an embodiment of the disclosure.

Throughout the drawings, like reference numerals will be understood torefer to like parts, components, and structures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thedisclosure. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of thedisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of thedisclosure is provided for illustration purpose only and not for thepurpose of limiting the disclosure as defined by the appended claims andtheir equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

Hereinafter, various embodiments of the disclosure will be describedbased on an approach of hardware. However, various embodiments of thedisclosure include a technology that uses both hardware and software,and thus the various embodiments of the disclosure may not exclude theperspective of software.

In the following description, terms (e.g., message, information,preamble, signal, signaling, sequence, and stream) referring to asignal, terms (e.g., symbol, slot, subframe, radio frame, subcarrier,resource element (RE), resource block (RB), bandwidth part (BWP), andoccasion) referring to a resource, terms (e.g., operation, andprocedure) referring to an operation state, terms (e.g., user stream,intelligence quotient (IQ) data, information, bit, symbol, and codeword)referring to data, terms referring to a channel, terms (e.g., downlinkcontrol information (DCI), medium access control (MAC) control element(CE), and radio resource control (RRC) signaling) referring to controlinformation, terms referring to network entities, terms referring toelements of a device, etc. are illustrated for the convenience ofdescription. Therefore, the disclosure is not limited to the termsdescribed below, and other terms having equivalent technical meaningsmay be used.

In the disclosure, in order to determine whether a specific condition issatisfied or fulfilled, an expression of more/greater/larger than orless/smaller than may be used, but this is only a description forexpressing an example, and does not exclude a description of equal to ormore/greater/larger than or a description of equal to or less/smallerthan. The condition described as “equal to or more/greater/larger than”may be replaced with “more/greater/larger than”, the condition describedas “equal to or less/smaller than” may be replaced with “less/smallerthan”, and the condition described as “equal to or more/greater/largerthan, and less/smaller than” may be replaced with “more/greater/largerthan, and equal to or less/smaller than”.

In the disclosure, various embodiments are described using terms used insome communication standards (e.g., 3rd generation partnership project(3GPP), extensible radio access network (xRAN), and open-radio accessnetwork (O-RAN)), but these are merely examples for description. Variousembodiments of the disclosure may also be easily modified and applied toother communication systems.

FIG. 1A illustrates a wireless communication system according to anembodiment of the disclosure.

Referring to FIG. 1A, it illustrates a base station 110, a terminal 120,and a terminal 130, as parts of nodes using a radio channel in awireless communication system. FIG. 1A illustrates only one basestation, but may further include another base station that is the sameas or similar to the base station 110.

The base station 110 is a network infrastructure that provides wirelessaccess to the terminals 120 and 130. The base station 110 has coveragedefined to be a predetermined geographic area based on the distance overwhich a signal may be transmitted. The base station 110 may be referredto as, in addition to “base station”, “access point (AP)”, “eNodeB(eNB)”, “5G node (5th generation node)”, “next generation nodeB (gNB)”,“wireless point”, “transmission/reception point (TRP)”, or other termshaving equivalent technical meanings.

Each of the terminal 120 and the terminal 130 is a device used by auser, and performs communication with the base station 110 via the radiochannel A link from the base station 110 to the terminal 120 or theterminal 130 is referred to as a downlink (DL), and a link from theterminal 120 or the terminal 130 to the base station 110 is referred toas an uplink (UL). The terminal 120 and the terminal 130 may communicatewith each other via a radio channel. In this case, a device-to-device(D2D) link between the terminal 120 and the terminal 130 is referred toas a sidelink, and the sidelink may be interchangeably used with a PC5interface. In some cases, at least one of the terminal 120 and theterminal 130 may be operated without involvement of a user. That is, atleast one of the terminal 120 and the terminal 130 is a device thatperforms machine type communication (MTC) and may not be carried by auser. Each of the terminal 120 and the terminal 130 may be referred toas, in addition to “terminal”, “user equipment (UE)”, “customer premisesequipment (CPE)”, “mobile station”, “subscriber station”, “remoteterminal”, “wireless terminal”, “electronic device”, “user device”, orother terms having equivalent technical meanings.

The base station 110, the terminal 120, and the terminal 130 may performbeamforming. The base station 110, the terminal 120, and the terminal130 may transmit and receive radio signals in a relatively low frequencyband (e.g., frequency range 1 (FR1) of new radio (NR)) as well as a highfrequency band (e.g., FR2 of NR, and a millimeter wave (mmWave) band(e.g., 28 GHz, 30 GHz, 38 GHz, and 60 GHz)). In some embodiments, thebase station may perform communication with the terminal within afrequency range corresponding to FR1. In some embodiments, the basestation may perform communication with the terminal within a frequencyrange corresponding to FR2. At this time, in order to improve a channelgain, the base station 110, the terminal 120, and the terminal 130 mayperform beamforming. The beamforming may include transmissionbeamforming and reception beamforming That is, the base station 110, theterminal 120, and the terminal 130 may assign a directivity to atransmission signal or a reception signal. To this end, the base station110 and the terminals 120 and 130 may select serving beams 112, 113,121, and 131 via a beam search procedure or a beam management procedure.After the serving beams 112, 113, 121, and 131 are selected,communication may then be performed via resources that are in quasico-located (QCL) relationship with resources at which the serving beams112, 113, 121, and 131 are transmitted.

If large-scale characteristics of a channel, via which a symbol on afirst antenna port has been transferred, can be inferred from a channelvia which a symbol on a second antenna port has been transferred, it maybe estimated that the first antenna port and the second antenna port arein a QCL relationship. For example, the large-scale characteristics mayinclude at least one among a delay spread, a Doppler spread, a Dopplershift, an average gain, an average delay, and a spatial receiverparameter.

Referring to FIG. 1A, it is illustrated that both the base station andthe terminal perform beamforming, but various embodiments are notnecessarily limited thereto. In some embodiments, the terminal may ormay not perform beamforming. The base station may or may not performbeamforming That is, only one of the base station and the terminal mayperform beamforming, or neither the base station nor the terminal mayperform beamforming.

In the disclosure, a beam refers to a spatial flow of a signal in aradio channel, and is formed by one or more antennas (or antennaelements), and this forming procedure may be referred to as beamformingBeamforming may include analog beamforming and digital beamforming(e.g., precoding). A reference signal transmitted based on beamformingmay be, for example, a demodulation-reference signal (DM-RS), a channelstate information-reference signal (CSI-RS), a synchronizationsignal/physical broadcast channel (SS/PBCH), and a sounding referencesignal (SRS). As a configuration for each reference signal, an internetexplorer (IE), such as a CSI-RS resource or an SRS-resource, may beused, and this configuration may include information associated with abeam. The information associated with a beam may indicate whether theconfiguration (e.g., CSI-RS resource) uses the same spatial domainfilter as that of the other configuration (e.g., another CSI-RS resourcein the same CSI-RS resource set) or uses a different spatial domainfilter, or may indicate a reference signal, with which the configurationis quasi-co-located (QCL), and a type (e.g., QCL type A, B, C, D) of theQCL if the configuration is quasi-co-located.

Referring to FIG. 1A, it is illustrated that both the base station andthe terminal perform beamforming, but various embodiments are notnecessarily limited thereto. In some embodiments, the terminal may ormay not perform beamforming. The base station may or may not performbeamforming That is, only one of the base station and the terminal mayperform beamforming, or neither the base station nor the terminal mayperform beamforming.

In a communication system of the related art in which a cell radius of abase station is relatively large, each base station is installed so thateach base station includes a function of a digital processing unit (orDU) and a function of a radio frequency (RF) processing unit (or RU).However, when a high frequency band is used in a communication system of4th generation (4G) and/or later, and as the cell radius of a basestation decreases, the number of base stations for covering a specificarea has increased, and the burden of installation costs of the operatorfor installation of the increased number of base stations has increased.In order to minimize an installation cost of a base station, a structurehas been proposed, the structure in which a DU and RUs of the basestation are separated so that one or more RUs are connected to one DUvia a wired network, and one or more RUs distributed geographically aredeployed to cover a specific area. Hereinafter, deployment structure andextension examples of the base station according to various embodimentswill be described via FIG. 1B.

FIG. 1B illustrates an example of a fronthaul structure according to afunction split of the base station according to an embodiment of thedisclosure. Unlike a backhaul between a base station and a core network,a fronthaul is located between entities between a WLAN and a basestation.

Referring to FIG. 1B, the base station 110 may include a DU 160 and anRU 180. A fronthaul 170 between the DU 160 and the RU 180 may beoperated via an Fx interface. For the operation of the fronthaul 170,for example, an interface, such as an enhanced common public radiointerface (eCPRI) and radio over Ethernet (ROE), may be used.

With the development of communication technology, mobile data trafficincreases, and accordingly, the amount of bandwidth required in afronthaul between a digital unit and a radio unit has greatly increased.In an arrangement, such as a centralized/cloud radio access network(C-RAN), the DU may be implemented to perform functions for a packetdata convergence protocol (PDCP), a radio link control (RLC), a mediaaccess control (MAC), and a physical (PHY) layer, and the RU may beimplemented to perform more functions for a PHY layer in addition to aradio frequency (RF) function.

The DU 160 may be in charge of an upper layer function of a radionetwork. For example, the DU 160 may perform a function of a MAC layerand a part of a PHY layer. Here, a part of the PHY layer is a functionperformed at a higher stage from among functions of the PHY layer, andmay include, for example, channel encoding (or channel decoding),scrambling (or descrambling), modulation (or demodulation), and layermapping (or layer demapping). According to an embodiment, if the DU 160conforms to the O-RAN standard, it may be referred to as an O-RAN DU(0-DU). The DU 160 may be replaced with and represented by a firstnetwork entity for the base station (e.g., gNB) in embodiments of thedisclosure as needed.

The RU 180 may be in charge of a lower layer function of the radionetwork. For example, the RU 180 may perform a part of the PHY layer andthe RF function. Here, a part of the PHY layer is a function performedat a relatively lower stage compared to the DU 160 from among thefunctions of the PHY layer, and may include, for example, an inversefast Fourier transform (IFFT) transformation (or FFT transformation),cyclic prefix (CP) insertion (CP removal), and digital beamforming. Anexample of such a specific function split is described in detail in FIG.4 . The RU 180 may be referred to as “access unit (AU)”, “access point(AP)”, “transmission/reception point (TRP)”, “remote radio head (RRH)”,“radio unit (RU)” or another term having an equivalent technical meaningAccording to an embodiment, if the RU 180 conforms to the O-RANstandard, it may be referred to as an O-RAN RU (O-RU). The DU 180 may bereplaced with and represented by a second network entity for the basestation (e.g., gNB) in embodiments of the disclosure as needed.

FIG. 1B shows that the base station includes the DU and the RU, butvarious embodiments are not limited thereto. In some embodiments, thebase station may be implemented to have distributed deployment accordingto a centralized unit (CU) configured to perform a function of an upperlayer (e.g., packet data convergence protocol (PDCP) and RRC) of anaccess network and a distributed unit (DU) configured to perform afunction of a lower layer. The distributed unit (DU) may include thedigital unit (DU) and the radio unit (RU) of FIG. 1B. Between the core(e.g., 5G core (5GC) or next generation core (NGC)) network and theradio network (RAN), the base station may be implemented in a structurewith deployment in the order of the CU, the DU, and the RU. An interfacebetween the CU and the distributed unit (DU) may be referred to as an F1interface.

The centralized unit (CU) may be connected to one or more DUs so as tobe in charge of a function of a layer higher than that of the DUs. Forexample, the CU may be in charge of functions of radio resource control(RRC) and packet data convergence protocol (PDCP) layers, and the DU andthe RU may be in charge of a function of a lower layer. The DU mayperform some functions of the physical (PHY) layer, the media accesscontrol (MAC), and the radio link control (RLC), and the RU may be incharge of the remaining functions (low PHY) of the PHY layer. Forexample, the digital unit (DU) may be included in a distributed unit(DU) according to distributed deployment implementation of the basestation. Hereinafter, unless otherwise defined, descriptions areprovided with operations of a digital unit (DU) and a RU. However,various embodiments may be applied to base station deployment includinga CU and/or deployment in which a DU is directly connected to a corenetwork without a CU (i.e., a CU and a DU are integrated and implementedinto one entity).

FIG. 2 illustrates a configuration of a DU in the wireless communicationsystem according to an embodiment of the disclosure. The configurationillustrated in FIG. 2 may be understood as the configuration of the DU160 of FIG. 1B, as part of the base station. The terms “-unit”,“-device”, etc. used hereinafter refer to a unit that processes at leastone function or operation, which may be implemented by hardware orsoftware, or a combination of hardware and software.

Referring to FIG. 2 , the DU 160 includes a communication unit 210, astorage unit 220, and a controller 230.

The communication unit 210 may perform functions for transmitting orreceiving a signal in a wired communication environment. Thecommunication unit 210 may include a wired interface for controlling adirect connection between devices via a transmission medium (e.g.,copper wire and optical fiber). For example, the communication unit 210may transfer an electrical signal to another device through a copperwire, or may perform conversion between an electrical signal and anoptical signal. The communication unit 210 may be connected to the radiounit (RU). The communication unit 210 may be connected to the corenetwork or may be connected to the CU in distributed deployment.

The communication unit 210 may perform functions for transmitting orreceiving a signal in a wired communication environment. For example,the communication unit 210 may perform conversion between a basebandsignal and a bit stream according to the physical layer specification ofa system. For example, when transmitting data, the communication unit210 generates complex symbols by encoding and modulating a transmissionbit stream. When receiving data, the communication unit 210 reconstructsa received bit stream by demodulating and decoding the baseband signal.Also, the communication unit 210 may include a plurality oftransmission/reception paths. According to an embodiment, thecommunication unit 210 may be connected to the core network or may beconnected to other nodes (e.g., integrated access backhaul (IAB)).

The communication unit 210 may transmit or receive a signal. To thisend, the communication unit 210 may include at least one transceiver.For example, the communication unit 210 may transmit a synchronizationsignal, a reference signal, system information, a message, a controlmessage, a stream, control information, data, or the like. Thecommunication unit 210 may perform beamforming.

The communication unit 210 transmits and receives a signal as describedabove. Accordingly, all or a part of the communication unit 210 may bereferred to as “transmitter”, “receiver”, or “transceiver”. In thefollowing description, transmission and reception performed via a radiochannel are used in a sense including processing performed as describedabove by the communication unit 210.

Although not illustrated in FIG. 2 , the communication unit 210 mayfurther include a backhaul communication unit for connecting to the corenetwork or another base station. The backhaul communication unitprovides an interface to perform communication with other nodes withinthe network. That is, the backhaul communication unit converts, into aphysical signal, a bit stream transmitted from the base station toanother node, for example, another access node, another base station, anupper node, the core network, etc., and converts a physical signalreceived from another node into a bit stream.

The storage unit 220 stores data, such as a basic program, anapplication program, and configuration information for operations of theDU 160. The storage unit 220 may include a memory. The storage unit 220may include a volatile memory, a nonvolatile memory, or a combination ofa volatile memory and a nonvolatile memory. The storage unit 220provides stored data in response to a request of the controller 230.

The controller 230 may control overall operations of the DU 160. Forexample, the controller 230 transmits and receives a signal via thecommunication unit 210 (or backhaul communication unit). Further, thecontroller 230 records and reads data in the storage unit 220. Thecontroller 230 may perform functions of a protocol stack required by thecommunication standard. To this end, the controller 230 may include atleast one processor. In some embodiments, the controller 230 may includea control message generator that generates a control plane messagehaving an extension field including a regularization factor, and amanagement message generator that generates a management message fordeactivating a regularization factor field of a message (e.g., a controlplane message of section Type 6 of O-RAN) including an existingregularization factor. The control message generator and the managementmessage generator are instruction sets/codes stored in the storage unit220, and may be instructions/codes which at least temporarily reside inthe controller 240, or storage spaces that store the instructions/codes,or may be a part of a circuitry constituting the controller 240.According to various embodiments, the controller 230 may control the DU160 to perform operations based on the various embodiments describedbelow.

The configuration of the DU 160 illustrated in FIG. 2 is merely anexample, and an example of the DU performing various embodiments of thedisclosure is not limited from the configuration illustrated in FIG. 2 .That is, according to various embodiments, some elements may be added,deleted, or changed.

FIG. 3 illustrates a configuration of an RU in the wirelesscommunication system according to an embodiment of the disclosure. Theconfiguration illustrated in FIG. 3 may be understood as theconfiguration of the RU 180 of FIG. 1B, as part of the base station. Theterms “-unit”, “-device”, etc. used hereinafter refer to a unit thatprocesses at least one function or operation, which may be implementedby hardware or software, or a combination of hardware and software.

Referring to FIG. 3 , the RU 180 includes a communication unit 310, astorage unit 320, and a controller 330.

The communication unit 310 performs functions for transmitting orreceiving a signal via a radio channel. For example, the communicationunit 310 up-converts a baseband signal into an RF band signal, transmitsthe up-converted RF band signal via an antenna, and then down-convertsthe RF band signal received via the antenna into a baseband signal. Forexample, the communication unit 310 may include a transmission filter, areception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC,and the like.

Also, the communication unit 310 may include a plurality oftransmission/reception paths. Further, the communication unit 310 mayinclude an antenna unit. The communication unit 310 may include at leastone antenna array including multiple antenna elements. In terms ofhardware, the communication unit 310 may include a digital circuit andan analog circuit (e.g., radio frequency integrated circuit (RFIC)). Thedigital circuit and the analog circuit may be implemented in a singlepackage. The communication unit 310 may include a plurality of RFchains. The communication unit 310 may perform beamforming. In order togive directivity according to a configuration of the controller 330 to asignal to be transmitted or received, the communication unit 310 mayapply a beamforming weight to the signal. According to an embodiment,the communication unit 310 may include a radio frequency (RF) block (orRF unit).

The communication unit 310 may transmit or receive a signal. To thisend, the communication unit 310 may include at least one transceiver.The communication unit 310 may transmit a downlink signal. The downlinksignal may include a synchronization signal (SS), a reference signal(RS) (e.g., cell-specific reference signal (CRS) and a demodulation(DM)-RS), system information (e.g., master information block (MIB),system information block (SIB), remaining system information (RMSI), andother system information (OSI)), a configuration message, controlinformation, downlink data, or the like. The communication unit 310 mayreceive an uplink signal. The uplink signal may include a randomaccess-related signal (e.g., a random access preamble (RAP) (or message1 (Msg1)) and message 3 (Msg3)) or a reference signal (e.g., a soundingreference signal (SRS), and a DM-RS), a power headroom report (PHR), orthe like.

The communication unit 310 transmits and receives a signal as describedabove. Accordingly, all or a part of the communication unit 310 may bereferred to as “transmitter”, “receiver”, or “transceiver”. In thefollowing description, transmission and reception performed via awireless channel are used in a sense including processing performed asdescribed above by the wireless communication unit 310.

The storage unit 320 stores data, such as a basic program, anapplication program, and configuration information for operations of theRU 180. The storage unit 320 may include a volatile memory, anonvolatile memory, or a combination of a volatile memory and anonvolatile memory. The storage unit 320 provides stored data inresponse to a request of the controller 330. According to an embodiment,the storage unit 320 may include a channel memory for updating channelinformation, without a memory that stores separate regularizationparameter-related information in real time.

The controller 330 controls overall operations of the RU 180. Forexample, the controller 330 transmits and receives a signal via thecommunication unit 310. The controller 330 records and reads data in thestorage unit 320. The controller 330 may perform functions of a protocolstack required by the communication standard. To this end, thecontroller 330 may include at least one processor. In some embodiments,the controller 330 may include a control message interpreter thatinterprets a message of a control plane (C-plane) having an extensionfield including a regularization factor, and a management messageinterpreter that interprets a message of a management plane (M-plane) todeactivate a regularization factor field of a message (e.g., a controlplane message of section Type 6 of O-RAN) including an existingregularization factor. The control message interpreter and a managementmessage interpreter, which are instruction sets or codes stored in thestorage unit 320, may be instructions/codes that are at leasttemporarily residing in the controller 330, or storage spaces that storethe instructions/codes, or may be a part of a circuitry constituting thecontroller 330. The controller 330 may include various modules forperforming communication. According to various embodiments, thecontroller 330 may control a terminal to perform operations based onvarious embodiments described below.

FIG. 4 illustrates an example of a function split in the wirelesscommunication system according to an embodiment of the disclosure. Withthe advancement of wireless communication technology (e.g., 5thgeneration communication system (or the introduction of new radio (NR)communication system)), a use frequency band has increased more andmore, and as a cell radius of a base station becomes very small, thenumber of RUs required to be installed has further increased. In a 5Gcommunication system, the amount of transmitted data has increased by 10times or more at most, and the transmission capacity of a wired network,which is transmitted via a fronthaul, has increased significantly. Dueto these factors, the installation cost of a wired network in a 5Gcommunication system may increase significantly. Therefore, in order tolower the transmission capacity of the wired network and reduce theinstallation cost of the wired network, techniques for lowering thetransmission capacity of the fronthaul by transferring some functions ofa modem of a DU to a RU have been proposed, and these techniques may bereferred to as “function split”.

In order to reduce the burden on the DU, a method of extending a role ofthe RU, which is in charge of only an RF function, to some functions ofa physical layer is considered. In this case, as the RU performsfunctions of a higher layer, the throughput of the RU increases, so thata transmission bandwidth in the fronthaul may increase, while delay timerequirement constraint due to response processing decreases. As the RUperforms the functions of a higher layer, the virtualization gaindecreases and the size/weight/cost of the RU increases. In considerationof the trade-off of the advantages and disadvantages described above, itis required to implement an optimal function split.

Referring to FIG. 4 , function splits in a physical layer below a MAClayer are shown. In the case of a downlink (DL) that transmits a signalto a terminal via the radio network, the base station may sequentiallyperform channel encoding/scrambling, modulation, layer mapping, antennamapping, RE mapping, digital beamforming (e.g., precoding), IFFTtransform/CP insertion, and RF conversion. In the case of an uplink (UL)that receives a signal from a terminal via the radio network, the basestation may sequentially perform RF conversion, FFT transform/CPremoval, digital beamforming (pre-combining), RE demapping, channelestimation, layer demapping, demodulation, and decoding/descrambling.Separation of uplink functions and downlink functions may be defined invarious types by the necessity between vendors, discussion onspecifications, etc. according to the trade-off described above.

A first function split 405 may be separation of an RF function and a PHYfunction. The first function split is that the PHY function in the RU isnot substantially implemented, and may be referred to as, for example,option 8. A second function split 410 enables the RU to perform the PHYfunction that is to perform IFFT transform/CP insertion in the DL andFFT transform/CP removal in the UL, and enables the DU to perform theremaining PHY functions. For example, the second function split 410 maybe referred to as option 7-1. A third function split 420 a enables theRU to perform the PHY function that is to perform IFFT transform/CPinsertion in the DL and FFT transform/CP removal and digital beamformingin the UL, and enables the DU to perform the remaining PHY functions.For example, the third function split 420 a may be referred to as option7-2x category A. A fourth function split 420 b enables the RU to performup to digital beamforming in both the DL and UL, and enables the DU toperform higher PHY functions after the digital beamforming. For example,the fourth function split 420 b may be referred to as option 7-2xcategory B. A fifth function split 425 enables the RU to perform up toRE mapping (or RE demapping) in both the DL and UL, and enables the DUto perform higher PHY functions after the RE mapping (or RE demapping).For example, the fifth function split 425 may be referred to as option7-2. A sixth function split 430 enables the RU to perform up tomodulation (or demodulation) in both the DL and UL, and enables the DUto perform higher PHY functions after the modulation (or demodulation).For example, the sixth function split 430 may be referred to as option7-3. A seventh function split 440 enables the RU to perform up toencoding/scrambling (or decoding/descrambling) in both the DL and UL,and enables the DU to perform higher PHY functions after theencoding/scrambling (or decoding/descrambling). For example, the seventhfunction split 440 may be referred to as option 6.

According to an embodiment, when large-capacity signal processing isexpected, such as the FR1 MMU, a function split (e.g., the fourthfunction split 420 b) at a relatively high layer may be required toreduce a fronthaul capacity. In a function split (e.g., the sixthfunction split 430) at a layer that is too high, a control interfacebecomes complex, and the burden on the implementation of the RU may becaused due to a plurality of PHY processing blocks included in the RU,so that an appropriate function split may be required according to adeployment and implementation scheme for the DU and the RU.

According to an embodiment, if precoding of data received from the DU isunable to be processed (i.e., if there is a limit to the precodingcapability of the RU), the third function split 420 a or a lowerfunction split (e.g., the second function split 410) may be applied.Conversely, if there is an ability to process the precoding of datareceived from the DU, the fourth function split 420 b or a higherfunction split (e.g., the sixth function split 430) may be applied.Hereinafter, various embodiments are described based on the thirdfunction split 420 a or fourth function split 420 b for performingbeamforming processing by the RU unless otherwise limited, butconfigurations of the embodiments via other function splits are notexcluded. The control plane message, management plane message, orconfiguration/operation flows of other devices in FIG. 5A to FIG. 11 ,which are described later may be applied to not only the third functionsplit 420 a or the fourth function split 420 b but also other functionsplits.

In various embodiments, when a message is transmitted between a DU(e.g., the DU 160 in FIG. 1B) and an RU (e.g., the RU 180 in FIG. 1B),an eCPRI and an O-RAN standards are exemplary as fronthaul interfaces.An eCPRI header, an O-RAN header, and an additional field may beincluded in an Ethernet payload of a message. Hereinafter, variousembodiments will be described using standard terms of the eCPRI orO-RAN, but other expressions having the equivalent meaning as each termmay be substituted and used in the various embodiments.

For a fronthaul transport protocol, Ethernet and eCPRI, which enableeasy sharing with a network, may be used. The eCPRI header and the O-RANheader may be included in the Ethernet payload. The eCPRI header may belocated at the front end of the Ethernet payload. The contents of theeCPRI header are as follows.

-   -   ecpriVersion (4 bits): 0001b (fixed value)    -   ecpriReserved (3 bits): 0000b (fixed value)    -   ecpriConcatenation (1 bit): Ob (fixed value)    -   ecpriMessage (1 byte): Message type    -   ecpriPayload (2 bytes): Payload size in bytes    -   ecpriRtcid/ecpriPcid (2 bytes): x, y, and z may be configured        via a management plane (M-plane). A corresponding field may        indicate a transmission path (extended antenna-carrier (eAxC) in        the eCPRI) of a control message according to various embodiments        during multi-layer transmission.    -   CU_Port_ID (x bits): A channel card is classified.        Classification is possible including up to a modem (2 bits for        channel card, and 2 bits for Modem).    -   BandSector_ID (y bits): Classification is performed according to        cell/sector.    -   CC_ID (z bits): Classification is performed according to a        component carrier.    -   RU_Port_ID (w bits): Classification is performed according to        layer, T, antenna, etc.    -   ecpriSeqid (2 bytes): A sequence identification (ID) is managed        for each ecpriRtcid/ecpriPcid, and a sequence ID and a        subsequence ID are separately managed. Radio-transport-level        fragmentation is possible if a subsequence ID is used (different        from application-level fragmentation).

An application protocol of the fronthaul may include a control plane(C-plane), a user plane (U-plane), a synchronization plane (S-plane),and a management plane (M-plane).

The control plane may be configured to provide the schedulinginformation and the beamforming information via the control message. Theuser plane may include user downlink data (IQ data or SSB/RS), uplinkdata (IQ data or SRS/RS), or PRACH data. A weight vector of theabove-described beamforming information may be multiplied by user data.The synchronization plane may be related to timing and synchronization.The management plane may be related to an initial setup, a non-realtimereset or reset, and a non-realtime report.

To define a type of a message transmitted in the control plane, asection type is defined. The section type may indicate the purpose of acontrol message transmitted in the control plane. For example, the useof each section type is as follows.

-   -   section Type=0: DL idle/guard periods—Tx blanking for power        saving purposes    -   sectionType=1: mapping a BF index or weight (O-RAN mandatory BF        scheme) to an RE of a DL/UL channel    -   sectionType=2: reserved    -   sectionType=3: mapping a beamforming index or weight to an RE of        a mixed-numerology channel and PRACH    -   sectionType=4: reserved    -   sectionType=5: transferring UE scheduling information so as to        enable an RU to calculate a real-time BF weight (O-RAN optional        BF scheme)    -   sectionType=6: periodically transferring UE channel information        so as to enable an RU to calculate a real-time BF weight (O-RAN        optional BF scheme)    -   sectionType=7: used for LAA support

When the RU communicates with a UE via beamforming, the RU requiresinformation on a current channel and scheduling information. That is,the RU is required to acquire a control message of section type 5 and acontrol message of section type 6. The RU may identify, from the controlmessage of section type 5, whether the UE is scheduled for each slot,and may identify information on a current channel state from the controlmessage of section type 6. The control message of section type 6 may betransferred periodically. Channel information may be transferredperiodically so as to enable the RU to calculate a beamforming weightfor each slot. Hereinafter, an example of a control message according tosection type 6 is described with reference to FIG. 5A.

FIG. 5A illustrates an example of a control message according to sectiontype 6 according to an embodiment of the disclosure. The control messageaccording to section type 6 is configured for the purpose of carryingchannel information.

Referring to FIG. 5A, the control message of section type 6 may includea transport header 501, a common header 503, first section information505, and second section information 507. The transport header 501 mayinclude a header according to an eCPRI or IEEE.

The common header 503 is a common radio application header, and mayinclude parameters as follows.

-   -   dataDirection (data direction (gNB Tx/Rx)) field: 1 bit    -   payloadVersion (payload version) field: 3 bits    -   value=“1” shall be set (1 st protocol version for payload and        time reference format)    -   filterIndex (filter index) field: 4 bits,    -   frameId (frame identifier) field: 8 bits    -   subframeId (subframe identifier) field: 4 bits    -   slotID (slot identifier) field: 6 bits    -   startSymbolid (start symbol identifier) field: 6 bits    -   numberOfsections (number of sections) field: 8 bits    -   sectionType (section type) field: 8 bits, value=6    -   numberOfUEs (number of UE-specific channel information data        sets) field: 8 bits    -   reserved (reserved for future use) field: 8 bits

The first section information 505 and the second section information 507may be configured for each UE. For example, the first sectioninformation 505 may be configured for a first UE, and the second sectioninformation may be configured for a second UE. Hereinafter, althoughdescriptions are provided based on the first section information 505,the same or similar format may be also applied to the second sectioninformation 507. The first section information 505 may includeparameters as follows.

-   -   ef (extension flag) field: 1 bit    -   ueId (UE identifier) field: 15 bits    -   regularizationFactor (regularization factor used for MMSE        reception) field: 16 bits    -   reserved (reserved for future use) field: 4 bits    -   rb (resource block identifier) field: 1 bit    -   symInc (symbol number increment command) field: 1 bit    -   startPrbc (starting PRB of data section description) field: 10        bits    -   numPrbc (number of contiguous PRBs per data section description)        field: 8 bits    -   ciIsample (channel information value, in-phase sample) field: 16        bits    -   ciQsample (channel information value, quadrature sample) field:        16 bits

Here, “regularizationFactor” is a parameter defined in the controlmessage of section type 6, and is transferred periodically. The“regularizationFactor” may provide a signaled value for support of aminimum mean square error (MMSE) operation by the RU, a DL/UL (e.g., thefourth function split of FIG. 4 ) of option 7-2x category B, or a ULwhen a beamforming weight is supported by the RU (e.g., option 7-2xcategory A (e.g., the third function split 420 a of FIG. 4 )). The“regularizationFactor” is 2 bytes (i.e., 16 bits), and indicates thevalue.

According to various embodiments, a regularization parameter indicatedby “regularizationFactor” may be used to derive a beamforming weight.For example, the relationship between the regularization parameter andthe beamforming weight may be derived based on the following equation.

$\begin{matrix}{G = {\frac{1}{\sqrt{\Psi}}\left( {{H^{H}H} + {\xi I_{M}}} \right)^{- 1}H^{H}}} & {{Equation}1}\end{matrix}$

Here, G denotes a beamforming weight matrix, Ψ denotes a powernormalized parameter for limiting full power, and ξ denotes aregularization parameter. H denotes a channel matrix. In addition toEquation 1, a plurality of methods may be used to calculate abeamforming weight. That is, various embodiments are not limited tocalculation of a beamforming weight from a regularization parameter byusing the method of Equation 1.

For example, a beamforming weight may be derived based on a channelcovariance parameter, and the relationship between the channelcovariance parameter and the regularization parameter may be derivedbased on the following equation.

R _(matrix) −HH ^(H) +R _(nn)  Equation 2

Here, R_(matrix) denotes a covariance matrix for interference/noise, Hdenotes a channel matrix, and R_(nn) denotes a regularization parameter.For example, when R_(nn) of “regularizationFactor” is 0, this mayrepresent zero forcing (ZF) beamforming (BF).

Hereinafter, the disclosure describes a device and method of a DU/RU,signaling, and a message for efficient processing of the above-describedregularization parameter (“regularizationFactor”). In the disclosure, aregularization parameter may be referred to and described as aregularization factor, regularization information, a regularizationelement, and the like. The embodiments are described using an example inwhich a regularization parameter is a 2-byte value of“regularizationFactor” of section type 6. However, in relation to ascheme for the size/calculation of data, transformation of the schemeinto a form, which is easy for a person skilled in the art, andexecution thereof may also be understood as an embodiment of thedisclosure.

FIG. 5B illustrates an example of a functional configuration of an RUfor beamforming information processing according to an embodiment of thedisclosure. An RU may include a channel memory 521 and a regularizationfactor memory 523.

Referring to FIG. 5B, the channel memory 521 may acquire channelinformation from a control message of section type 6. The RU may storethe channel information in the channel memory 521. The channelinformation may be periodically updated. For example, the channelinformation may be “ciIsample (Ci)” or “ciQsample (Cq)” of section type6, or may include a value obtained therefrom. Ci denotes an I value ofcomplex channel information, and Cq denotes a Q value of the complexchannel information. The regularization factor memory 523 may obtaininformation on a regularization parameter from the control message ofsection type 6. The regularization parameter is also transferred(updated) when the channel information is transferred (updated) inC-plane section type 6. The RU may store information on theregularization parameter in the regularization factor memory 523. Inthis case, the information on the regularization parameter may beperiodically updated. For example, the information on the regularizationparameter may be “regularization factor” of section type 6, or mayinclude a value obtained therefrom. The regularization factor memory 523may be referred to as an R_(nn) memory (e.g., R_(nn) is a regularizationparameter value of Equation 2).

A control message of section type 5 may include scheduling informationof a UE. Scheduling may be performed in a specified unit (e.g., slotunit). The scheduling information may be repeatedly provided to theregularization factor memory 523 for each slot. Information on theregularization parameter is transferred along with the channelinformation, and the RU may thus include the regularization factormemory 523 of the same level as the channel memory 521 which is a memorystoring the channel information. The RU may acquire a correspondingchannel value and regularization parameter value from each memory so asto calculate a beamforming weight, according to scheduling information(e.g., the control message of section type 5) transferred for each slot.Specifically, in order to calculate the beamforming weight, the RU mayacquire the channel information from the channel memory 521 and mayacquire the regularization parameter from the regularization factormemory 523. The RU may calculate and acquire a beamforming weight (ormulti-user (MU) weight) for MMSE (or ZFBF) for a current channel, basedon the regularization parameter and the channel information.

Although the beamforming weight needs to be calculated only when the UEis scheduled, the regularization factor memory 523 periodically acquiresand stores channel information and a regularization parameter inaddition to the scheduling information acquired each time when the UE isscheduled. When the UE is actually scheduled, a most recentlytransferred regularization parameter value should be used, and thereforethe regularization factor memory 523 is required to store alltransferred regularization parameter values even if the values are notactually used. Therefore, information on the regularization parameter,which is repeatedly stored even though the UE is not actually scheduled,causes a burden on the regularization factor memory 523. In addition, ifthe channel information is updated for a relatively long period comparedto the scheduling information updated in every slot (e.g., 0.5 ms), aprobability that the regularization parameter of section type 6 does notcorrectly reflect a channel actually experienced by the UE increases. Aspecific example is described via FIG. 5C.

FIG. 5C illustrates a relationship between a regularization factor andscheduling according to an embodiment of the disclosure.

Referring to FIG. 5C, upward-pointing arrows indicate that a“regularization factor” of a control message of section type 6 for UE #3is transferred. A transfer period 540 of the control message may be 40ms. Multiple UEs may be scheduled. UE #3 may be scheduled at each of afront end 551 and a rear end 553 within a period 540 of 40 ms.

If UE #3 is scheduled in the front end 551, since a relatively smallamount of time has elapsed after channel information of section type 6is updated, an RU may derive a beamforming weight that is moreconsistent with an actual channel. However, if UE #3 is scheduled at therear end 553, since a relatively long time has elapsed after channelinformation of section type 6 is updated, it is difficult for the RU toderive a beamforming weight that is more consistent with an actualchannel. This is because a channel changes over time, so that adifference occurs between an actual channel and a channel appearing inchannel information transferred via a DU. Such a problem causes a largererror when a transfer period of the control message of section type 6 islonger, and this error causes an incorrect beamforming weight to begenerated, resulting in a decrease in transmission performance.

Hereinafter, various embodiments describe a method for transferring aregularization parameter along with transferring of schedulinginformation, instead of periodically transferring a regularizationparameter, in order to resolve the problems described via FIG. 5A toFIG. 5C. Various embodiments describe a processing method of“regularizationFactor”, which is periodically transferred, of sectiontype 6 defined in the existing O-RAN standard, in order to satisfybackward compatibility. Various embodiments describe a method of newfunctional implementation of an RU, in order to avoid a memory burden instoring periodically transferred information.

In the disclosure, not only transferring of scheduling/channelinformation for a 5G communication system (e.g., NR) but alsoimplementation for a 4G communication system (e.g., LTE) may beunderstood as an embodiment of the disclosure. That is, thecommunication system, in which DU and RU operations described later areprovided, is neither limited only to the 5G communication system norlimited only to the 4G communication system.

FIG. 6 illustrates an example of an extension field according to anembodiment of the disclosure. When a control message according to anexisting section type is transmitted, a DU may transmit additionalinformation along with the control message via an extension field. Thatis, the DU may transmit the control message on a control plane sectionby attaching a new extension field, a “section extension” field.

Referring to FIG. 6 , a section extension field 600 according to variousembodiments may include information on a regularization parameter. Theregularization parameter may be a value corresponding to“regularizationFactor” of section type 6.

-   -   extType may indicate a type for an additional parameter.        According to an embodiment, if extType indicates 11, extType may        indicate that an additional parameter includes a value of a        regularization factor for MMSE (or ZFBF). A value of “11” is        exemplary and, of course, another number for designating the        type for the parameter may be assigned.    -   ef may indicate whether an additional section extension field        exists. An ef value of “1” indicates that there is an additional        section extension field, and an ef value of “0” indicates that        there is no additional section extension field.    -   extLen may indicate a length of a section extension field in        units of 4 bytes. According to an embodiment, extLen may        indicate 1.

A section extension field including a regularization parameter accordingto various embodiments may be attached to a control message (e.g., acontrol plane message of section type 5 of O-RAN) including schedulinginformation so as to be transmitted along with the control message. Aproblem of being incapable of reflecting an actual channel state whencalculating a beamforming weight, due to the difference between ascheduling time and a transfer time of a regularization parameter may beresolved by transferring the regularization parameter along withscheduling information by the DU.

Although not illustrated in FIG. 6 , a section extension field includingchannel information may be defined. For example, a section extensionfield including channel information (e.g., ciIsample and ciQsample)within a control message of section type 6 may be defined. The channelinformation in the section extension field may be configured for eachfrequency resource (e.g., a PRB, a PRB group, a bandwidth part (BWP),etc.) for each antenna. By considering capability of a terminal that anRU intends to serve and/or rank information of the terminal, the DU mayacquire the number of required antennas among all antennas. When arelatively small amount of channel information is required according toa type of communication scheme (e.g., LTE), or by considering ascheduling area for a specific terminal, the DU may identify a frequencydomain which is actually serviced to the terminal from among resourcesof the entire frequency domain.

In some embodiments, the channel information may include channelinformation for each of all antennas and channel information for each ofall PRBs. In some other embodiments, the channel information may includechannel information for each of some antennas among all antennas andchannel information for each of some PRBs among all PRBs. In some otherembodiments, the channel information may include channel information foreach of some antennas among all antennas and channel information foreach of all PRBs. In some other embodiments, the channel information mayinclude channel information for each of all antennas and channelinformation for each of some PRBs. According to an embodiment, bytransferring channel information for an actual scheduling area of theterminal, channel information having a relatively small capacity may beconfigured as a section extension field.

Instead of being periodically transferred as in section type 6, channelinformation may be attached to section type 5, via which schedulinginformation is transmitted, so as to be transferred to the RU in theform of a section extension field. Like a regularization parameter, byproviding channel information during actual scheduling of the terminal,a problem of deterioration of communication performance due to thedifference between a channel information transferring time and an actualscheduling time may be solved. In addition, if accurate channelinformation is irregularly required as necessary, the RU may obtain anoptimal beamforming weight via a section extension field.

According to an embodiment, a section extension field including channelinformation may be configured as shown in the following table. Thesection extension field including channel information may be attached toa control message (e.g., a control message of section type 5 of theC-plane) including scheduling information of a terminal (UE) so as to betransmitted.

TABLE 1 0 1 2 3 4 5 6 7 ef extType = 0x12 1 Octet N extLen = 0x02 1Octet N + 1 ciIsample (first PRB, first antenna) 2 Octet N + 2 Octet N +3 ciQsample (first PRB, first antenna) 2 Octet N + 4 Octet N + 5reserved 1 Octet N + 6 reserved 1 Octet N + 7

According to an embodiment, a section extension field including channelinformation may be configured as shown in the following table. Thesection extension field including channel information may includeinformation on “regularizationFactor”, that is, a regularizationparameter. The section extension field including both channelinformation and regularization parameter information may be attached toa control message (e.g., a control message of section type 5 of theC-plane) including scheduling information of a terminal (UE) so as to betransmitted.

TABLE 2 0 1 2 3 4 5 6 7 ef extType = 0x13 1 Octet N extLen = 0x02 1Octet N + 1 regularizationFactor 2 Octet N + 2 Octet N + 3 ciIsample(first PRB, first antenna) 2 Octet N + 4 Octet N + 5 ciQsample (firstPRB, first antenna) 2 Octet N + 6 Octet N + 7

In Tables 1 and 2, ciIsample and ciQsample for one antenna/one PRB areillustrated for the channel information, but various embodiments are notlimited thereto. The section extension field may be defined for a largernumber of antennas or a larger number of PRBs. For example, the lengthsof ciIsample and ciQsample may be variable and may be configured byM-plane.

Even if a regularization parameter is transferred along with schedulinginformation via the section extension field, the regularizationparameter transferred via a control message of section type 6 of theexisting standard (e.g., O-RAN 2.00) is periodically transferred to theRU. A memory of the RU periodically receives regularization parameters,and therefore the control message of section type 6 is still a burden.Hereinafter, various embodiments propose a method for reducing theinfluence of “regularizationFactor” of the control message of sectiontype 6 while satisfying backward compatibility with the existingstandard.

FIG. 7 illustrates an example of a management message for section type 6according to an embodiment of the disclosure. A management messagerefers to a message transferred in a management plane (M-plane) ofO-RAN. The DU may perform packet communication with an RU in amanagement area within a main card. The management message may betransmitted from the DU to the RU or from the RU to the DU. In themanagement plane, “start up” installation, software management,configuration management, performance management, fault management, andfile management may be performed.

Referring to FIG. 7 , the DU may generate a management message. Amanagement message according to various embodiments may be a message forconfiguration to the RU so that “regularization factor” of a controlmessage of section type 6 is invalid. In some embodiments, themanagement message may include a parameter (hereinafter, a selectionparameter) indicating selection of a transfer medium. The selectionparameter may indicate whether to transfer a regularization parametervia a message of section type 6 of the control plane or to transfer theregularization parameter via a section extension field as before. Forexample, a selection parameter value of “0” may indicate transferring ofthe regularization parameter via the message of section type 6. Aselection parameter value of “1” may indicate transferring of theregularization parameter via the section extension field. If theselection parameter value indicates transferring of the regularizationparameter via the section extension field, a regularizationFactor valuein the control message of section type 6 is invalid. The RU havingreceived the management message including the selection parameter valuemay not consider the regularizationFactor value of section type 6. Forexample, the RU may ignore or discard the regularizationFactor value ofsection type 6 that is periodically transmitted. For example, the RU maynot consider the regularizationFactor value for a specified period.

The DU may transmit the management message to the RU. The RU mayidentify a method of obtaining the regularization parameter from themanagement message. For example, the RU may obtain a regularizationparameter from the section extension field. For another example, the RUmay obtain the regularization parameter from section type 6.

Although not illustrated in FIG. 7 , fields in the existing section type6 may be used for backward compatibility. In some embodiments, if“regularizationFactor” indicates a specific value (e.g., 1111 1111 11111111), a field value of “regularizationFactor” may be an invalid value.The RU may ignore or discard the corresponding “regularizationFactor”without storing the same. In some other embodiments, if at least one bitin a reserved bit among fields in the existing section type 6 indicatesa specific value (e.g., 1), a field value of “regularizationFactor” maybe an invalid value. The RU may ignore or discard the corresponding“regularizationFactor” without storing the same. In still some otherembodiments, it may be indicated that a field value of“regularizationFactor” is an invalid value, via a combination of atleast two of fields in the existing section type 6.

According to various embodiments, in a situation where it is difficultto transmit a message (e.g., the control message of section type 6) forperiodic transferring of channel information (e.g., or if the amount ofmemory allocation of the RU becomes bulky, or the capacity of the RU isinsufficient), or in a case where a transmission capacity of a fronthaulis sufficiently large, the DU may transfer additional information alongwith scheduling information via the section extension field. Theadditional information may include information replacing information inthe control message of section type 6. For example, the additionalinformation may include channel information. For example, the additionalinformation may include information on the regularization parameter. Viatransmission of the additional information via the section extensionfield, the DU may perform replacement of section type 6 via a controlmessage of section type 5.

FIG. 8A illustrates an operation flow of a DU for an extension fieldaccording to an embodiment of the disclosure. A DU illustrates the DU160 of FIG. 2 .

Referring to FIG. 8A, in operation 801, the DU may configure a sectionextension field including a regularization parameter. The regularizationparameter may be a parameter for deriving a beamforming weight. Thebeamforming weight may be a matrix configured so that a valid channelmatrix experienced by a transmitted signal is able to smoothly reach areception end. According to an embodiment, the beamforming weight may bederived based on MMSE or zero-forcing beamforming (ZFBF). For example,the beamforming weight may be derived by Equation 1 described above.This regularization parameter may be a value indicated by a“regularization factor” field within a control message of section type 6of the O-RAN standard.

In operation 803, the DU may transmit a control message for scheduling,which includes the section extension field, to an RU. The DU mayconfigure the control message for scheduling. That is, the DU maygenerate a message including scheduling information of a UE, in acontrol message of a C-plane. For example, the DU may generate a controlmessage of section type 5. The DU may attach an extension section fieldto the control message. Here, the extension section field may be asection extension field configured in operation 801. The DU may transmitthe control message to the RU via a fronthaul interface. That is, viathe control message for scheduling, scheduling information for aterminal and a regularization parameter for a channel may be transferredtogether to the RU.

FIG. 8B illustrates an operation flow of an RU for an extension fieldaccording to an embodiment of the disclosure. An RU illustrates the RU180 of FIG. 2 .

Referring to FIG. 8B, in operation 851, the RU may receive a controlmessage for scheduling. The control message may include schedulinginformation for a UE. For example, the control message may correspond toa message of section type 5 of a C-plane of O-RAN. The RU may receivethe control message from a DU via a fronthaul interface.

In operation 853, the RU may identify the regularization parameter froma section extension field in the control message. The RU may identifythe section extension field in the control message. The RU may determinewhat information is included in the section extension field, from typeinformation (e.g., extType) of the section extension field. The RU maydetermine that the section extension field includes the regularizationparameter, from a specified type value. The RU may identify theregularization parameter. For example, the regularization parameter maybe indicated with a 2-byte value.

In operation 855, the RU may obtain a beamforming weight. Thebeamforming weight may be a beamforming weight for multi-users (MU). TheRU may derive the beamforming weight based on the regularizationparameter obtained in operation 853. For example, the RU may derive thebeamforming weight based on Equation 1. For example, the RU may derivethe beamforming weight from an R_(nn) value based on Equation 2.

Although not illustrated in FIG. 8A and FIG. 8B, channel information inthe control message for scheduling may be additionally included. Here,the channel information may be I/Q data for complex channel informationin a resource (e.g., x PRB, where x is an integer smaller than or equalto 273) allocated to a terminal/an antenna of the terminal.

FIGS. 8A and 8B describe a method for reducing an error due to anacquisition time difference of channel information and improvingtransmission performance, by transmitting the regularization parameterincluded in existing section type 6 via adding the extension field tothe control message including the channel information. However, if theregularization parameter of section type 6 is transmitted via theextension section field without separate processing of theregularization parameter, there occurs a problem that a work capacity ina memory of the RU becomes too bulky. Specifically, section type 6 istransmitted periodically, while scheduling is performed in units muchshorter than the above period, so that, in order to calculate thebeamforming weight by reflecting real-time channel information, thereoccurs a problem of storing information (e.g., the channel informationand the regularization parameter) relating to a channel for eachscheduling unit during the period. Accordingly, a method fordeactivating (or invalidating) the regularization parameter of thecontrol message of existing section type 6, which is periodicallytransferred, is described.

FIG. 9A illustrates an operation flow of a DU for a management messagefor section type 6 according to an embodiment of the disclosure. A DUillustrates the DU 160 of FIG. 2 .

Referring to FIG. 9A, in operation 901, the DU may transmit a managementmessage for a regularization parameter. The DU may transmit themanagement message to an RU via a fronthaul interface. The managementmessage may be a message transferred from the DU to the RU on anM-plane. The management message is a non-real time message and may betransmitted in a main card of the DU. The management message for theregularization parameter may be a message indicating a method foracquiring the regularization parameter by the RU. In some embodiments,the management message may indicate whether the regularization parameteris transferred via a section extension field or transferred via acontrol message for channel information. For example, the managementmessage may include 1 bit. The 1 bit may indicate a transfer scheme of aregularization parameter. For example, “1”, i.e., the value of 1 bit,may indicate that the regularization parameter is transferred via thesection extension field. “0”, i.e., the value of 1 bit, may indicatethat the regularization parameter is transferred via a control messageof section type 6 (C-plane).

In some embodiments, the management message may include informationrelating to validity of the regularization parameter of the controlmessage for channel information. For example, the management message mayindicate, with 1 bit, whether “regularizationFactor” in the controlmessage of section type 6 is valid. A value of “1” may indicate that theregularization parameter in section type 6 is invalid. The value of “1”may implicitly indicate that the regularization parameter is transferredvia the section extension field. The value of “0” may indicate that theregularization parameter in section type 6 is valid.

In some embodiments, the management message may include informationrelating to the validity of the regularization parameter of theextension section field. For example, the management message mayindicate, with 1 bit, whether “regularizationFactor” in the sectionextension field is valid. The value of “1” may indicate that theregularization parameter in the section extension field is invalid. Thevalue of “1” may implicitly indicate that the regularization parameteris transferred via section type 6. The value of “0” may indicate thatthe regularization parameter in the section extension field is valid.For example, the management message may include information on avalidity period of the regularization parameter of the extension sectionfield. The regularization parameter of the control message of sectiontype 6 may be configured to default, and the regularization parameter ofthe extension section field may be provided to the RU as needed. In thiscase, during the validity period according to the management message,only the regularization parameter of the extension section field may bereceived, and the regularization parameter of the control message ofsection type 6 may be ignored or discarded.

In operation 903, the DU may transmit the control message for thechannel information, which includes the regularization parameter. The DUmay transmit the control message to the RU via the fronthaul interface.The control message may be configured to include the channelinformation, and may be periodically transferred from the DU to the RU.For example, the control message may be a message of section type 6 ofO-RAN, and the regularization parameter may be “regularizationFactor”.

The DU may configure whether the regularization parameter for a channelis valid, to the RU via the management message, so that even if the DUtransmits the management message as in the existing standard, the RU mayefficiently process the regularization parameter. That is, backwardcompatibility may be satisfied.

FIG. 9B illustrates an operation flow of an RU for a management messagefor section type 6 according to an embodiment of the disclosure. An RUillustrates the RU 180 of FIG. 2 .

Referring to FIG. 9B, in operation 951, the RU may receive a managementmessage for a regularization parameter. The RU may receive themanagement message from a DU via a fronthaul interface. The managementmessage is a message transferred in an M-plane and may be transferred ina main card of the DU. The management message for the regularizationparameter may include information on a scheme of transferring theregularization parameter. In some embodiments, the management messagemay indicate whether the regularization parameter is transferred via asection extension field or transferred via a control message for channelinformation. In some embodiments, the management message may includeinformation relating to the validity of a regularization parameter ofsection type 6. In some embodiments, the management message may includeinformation on the validity of the regularization parameter transferredvia the section extension field.

In operation 953, the RU may identify a transfer scheme of theregularization parameter. The RU may identify a transfer scheme of theregularization parameter, based on the management message received fromthe DU. For example, the RU may acquire the regularization parameteronly via the control message (e.g., the control message of section type6) for the channel information. For example, the RU may acquire theregularization parameter only via the section extension field. Forexample, the RU may acquire the regularization parameter via at leastone of the section extension field or the control message for thechannel information.

In operation 955, the RU may receive the control message for the channelinformation, which includes the regularization parameter. The RU mayreceive the control message from the DU via the fronthaul interface. TheRU may determine whether acquisition of the regularization parameter isallowed via the control message for the channel information. Ifacquisition of the regularization parameter via the control message forthe channel information is allowed, the RU may acquire theregularization parameter from the control message (e.g., the controlmessage of section type 6). The RU may determine a beamforming weightbased on the acquired regularization parameter.

If acquisition of the regularization parameter via the control messagefor the channel information is not allowed, the RU may ignore or discardthe regularization parameter of the control message (e.g., the controlmessage of section type 6) for the channel information. According to anembodiment, if scheduling information is received, the RU may acquirethe regularization parameter from an extension field in the controlmessage including the scheduling information. The RU may determine thebeamforming weight based on the acquired regularization parameter.

Although not illustrated in FIGS. 9A and 9B, a control message inaddition to the management message may be used to indicate a scheme oftransferring a regularization parameter. The management message may betransferred in a main card of the DU to the RU, and the control messagemay be transferred from a channel card of the DU to the RU. The controlmessage may be transmitted in real time relative to the managementmessage. According to an embodiment, it may be indicated that“regularizationFactor” in the control message of section type 6 isinvalid, via a partial value of “regularizationFactor” or a partialfield of the control message.

FIG. 10 illustrates an example of a functional configuration of an RUfor beamforming information processing according to an embodiment of thedisclosure. An RU may include a channel memory 1021.

Referring to FIG. 10 , the channel memory 1021 may acquire channelinformation from a control message of section type 6. The RU may storethe channel information in the channel memory 1021. The channelinformation may be periodically updated. For example, the channelinformation may be “ciIsample (Ci)” or “ciQsample (Cq)” of section type6, or may include a value obtained therefrom. Ci denotes an I value ofcomplex channel information, and Cq denotes a Q value of the complexchannel information. The RU may ignore or discard information on aregularization parameter in the control message of section type 6. TheRU may identify that the regularization parameter in the control messageof section type 6 is invalid. According to an embodiment, the RU mayidentify that the regularization parameter in the control message of acontrol plane of section type 6 is invalid, based on a managementmessage of a management plane from a DU. According to an embodiment, theRU may identify that the regularization parameter in the control messageof section type 6 is invalid, based on a control message of the DU.

The RU may transfer scheduling information of section type 5 to achannel memory 1021. The channel memory 1021 may store schedulinginformation in units of slots (scheduling unit), and may use a channelinformation result according thereto when a beamforming weight iscalculated. The channel memory 1021 may output channel information inunits of slots, and an output result may be used when a beamformingweight is calculated.

The RU may acquire a regularization parameter from a section extensionfield transferred along with section type 5. Unlike the description inFIG. 5B, the RU according to various embodiments may not include aregularization factor memory. That is, the RU may be configured not tostore a regularizationFactor value of the control message of sectiontype 6, which is periodically transferred. Due to causing of a memoryburden, the RU may be configured to acquire only the regularizationparameter of the section extension field. Therefore, the RU acquires theregularization parameter via the section extension field in a controlmessage including scheduling information, that is, the control messageof section type 5, so that the acquired regularization parameter may beused directly to calculate the beamforming weight. This is because aterminal is scheduled in a corresponding slot, and it is thus expectedto determine a beamforming weight directly.

By transferring the regularization parameter value (i.e., R_(nn) value)via the section extension field, the regularization parameter may bedirectly transferred to a beamforming weight calculator without aseparate memory (e.g., the regularization factor memory 523 in FIG. 5B)for storing the regularization parameter. Since the regularizationparameter transferred via the extension field corresponds to a channelactually used, accuracy thereof is improved compared to theregularization parameter transferred via existing section type 6. Anupdate time of the regularization parameter and a use time of theregularization parameter are almost the same, and therefore a decreasein transmission performance due to a channel error may be reduced. Inaddition, a separate memory for storing the regularization parameter ofsection type 6 is not required, and therefore implementation of the RUmay be more simplified.

Although not illustrated in FIG. 10 , a DU or the RU may further includea multiplexer (MUX). The MUX may configure, as an input, theregularization parameter of the extended field in the control message ofsection type 5 and the regularization parameter in the control messageof section type 6. The MUX may select an output based on a message of anM-plane. If the message of the M-plane allows transfer of theregularization parameter by the section extension field, the MUX mayoutput the regularization parameter of the control message of sectiontype 5. The RU may calculate a beamforming weight based on the outputregularization parameter. If the message of the M-plane does not allowtransfer of the regularization parameter by the section extension field,the MUX may output the regularization parameter of the control messageof section type 6. The RU may calculate a beamforming weight based onthe corresponding regularization parameter. A central processing unit(CPU) of the DU that generates a message in the control plane may alsoprovide one output to the RU via the MUX.

FIG. 11 illustrates a relationship between a regularization factor andscheduling according to an embodiment of the disclosure.

Referring to FIG. 11 , upward-pointing arrows indicate that a“regularization factor” of a control message of section type 5 for UE #3is transferred. Unlike illustrated in FIG. 5C, a valid “regularizationfactor” may be transferred according to a scheduling time of UE #3,instead of being transferred periodically. The regularization factor isupdated immediately before UE #3 is scheduled, and therefore an RU mayderive a beamforming weight more consistent with an actual channel.Accordingly, as shown in FIG. 5C, regardless of whether the RU islocated at the front end 551 or the rear end 553 within a schedulingperiod, the RU may acquire an optimal beamforming weight.

Although not illustrated in FIG. 11 , according to an embodiment,channel information may be transferred along with a regularizationparameter via section type 5. By transfer of not only the regularizationparameter but also actual channel state information (per antenna, perPRB) with the regularization parameter, the RU may acquire a beamformingweight more consistent with the actual channel.

FIG. 12 illustrates an example of a relationship between DUs and RUs viaa section extension field according to an embodiment of the disclosure.A section extension field according to various embodiments may beconfigured to replace a control message of section type 6. In someembodiments, the section extension field may include information on aregularization parameter. In some embodiments, the section extensionfield may include channel information.

Referring to FIG. 12 , a DU may be connected to a plurality of RUs. AnRU conforms to the O-RAN standard, and may be thus referred to as anO-RU. The DU may be connected to an X number of O-RUs. The DU may beconnected to O-RU #0, O-RU #1, O-RU #2, . . . , to O-RU #X-1. Accordingto an embodiment, some of the O-RUs may periodically acquire channelinformation via section type 6. On the other hand, some other 0-RUs mayacquire channel information via the section extension field according tovarious embodiments. The transfer scheme (e.g., a scheme of transferringa regularization parameter) for each 0-RU, that is, whether the transferis performed via section type 6 or via the section extension field, maybe determined based on a management plane parameter (M-plane parameter)according to an embodiment. Via the M-plane parameter, whether totransfer channel-related information (e.g., regularization parameter)via section type 6 or to transfer channel-related information via asection extension field including optional additional information may beselected. The DU may configure this to each RU via the M-planeparameter.

According to embodiments, an operation method of a digital unit (DU) ofa base station in a wireless communication system. the method comprises:configuring a section extension field comprising additional information;and transmitting a first control message comprising the sectionextension field to a radio unit (RU) via a fronthaul interface, whereinthe first control message is configured to schedule a terminal in acontrol plane.

In some embodiments, the first control message corresponds to a controlmessage of section type 5 of an open-radio access network (O-RAN), andthe first control message comprises scheduling information on theterminal.

In some embodiments, the method further comprises: transmitting amanagement message related to the section extension field, wherein themanagement message is configured in a management plane.

In some embodiments, the additional information comprises aregularization parameter.

In some embodiments, the method further comprises: configuring thesection extension field so as to comprise the regularization parameter;and transmitting the first control message comprising the sectionextension field that comprises the regularization parameter, wherein thefirst control message comprising the section extension field thatcomprises the regularization parameter is configured to schedule theterminal in the control plane.

In some embodiments, the method further comprises: transmitting amanagement message related to the regularization parameter; andtransmitting a second control message comprising the regularizationparameter to the RU, wherein the second control message is configured toperiodically transmit channel information in the control plane, and themanagement message is configured in a management plane.

In some embodiments, the second control message corresponds to a messageof section type 6 of an open-radio access network (O-RAN), and thesecond control message comprises channel information.

In some embodiments, the regularization parameter is used to calculate abeamforming weight for a minimum mean square error (MMSE) operation, andthe regularization parameter corresponds to a regularizationFactor fieldof a message of section type 6 of an open-radio access network (O-RAN).

According to embodiments, an operation method of a radio unit (RU) of abase station in a wireless communication system. The method comprises:receiving a first control message comprising a section extension fieldfrom a digital unit (DU) via a fronthaul interface; identifyingadditional information based on the section extension field; andacquiring a beamforming weight based on the additional information,wherein the first control message is configured to schedule a terminalin a control plane.

In some embodiments, the method further comprises: receiving amanagement message related to the section extension field, wherein themanagement message is configured in a management plane.

In some embodiments, the additional information comprises aregularization parameter.

In some embodiments, the first control message corresponds to a controlmessage of section type 5 of an open-radio access network (O-RAN), andthe first control message comprises scheduling information on theterminal.

In some embodiments, the method further comprises: receiving amanagement message related to the regularization parameter, which isconfigured in a management plane, from the DU; based on the managementmessage, identifying, as a scheme of transferring the regularizationparameter, at least one scheme of a scheme via the first control messageor a scheme via a second control message configured to periodicallytransmit channel information in the control plane; receiving the secondcontrol message comprising another regularization parameter from the DU;identifying one of the regularization parameter or the otherregularization parameter according to the at least one scheme; andacquiring the beamforming weight based on the identified one of theregularization parameter or the other regularization parameter.

In some embodiments, the second control message corresponds to a messageof section type 6 of an open-radio access network (O-RAN), and thesecond control message comprises the channel information.

In some embodiments, the regularization parameter is used to calculatethe beamforming weight for a minimum mean square error (MMSE) operation,and the regularization parameter corresponds to a regularizationFactorfield of a message of section type 6 of an open-radio access network(O-RAN).

According to embodiments, a device of a digital unit (DU) of a basestation in a wireless communication system, the device comprising:

-   -   at least one transceiver; and    -   at least one processor coupled to the at least one transceiver,        wherein the at least one processor is configured to:    -   configure a section extension field comprising a regularization        parameter; and    -   transmit a first control message comprising the section        extension field to a radio unit (RU) via a fronthaul interface,        wherein the first control message is configured to schedule a        terminal in a control plane.

In some embodiments, additional information comprises the regularizationparameter.

In some embodiments, the at least one processor is further configuredto: configure the section extension field so as to comprise theregularization parameter; and transmit the first control messagecomprising the section extension field which comprises theregularization parameter, wherein the first control message comprisingthe section extension field which comprises the regularization parameteris configured to schedule the terminal in the control plane.

In some embodiments, the first control message corresponds to a controlmessage of section type 5 of an open-radio access network (O-RAN), andthe first control message comprises scheduling information on theterminal.

In some embodiments, the at least one processor is further configuredto: transmit a management message related to the regularizationparameter; and transmit a second control message comprising theregularization parameter to the RU, wherein the second control messageis configured to periodically transmit channel information in thecontrol plane, and the management message is configured in a managementplane.

In some embodiments, the second control message corresponds to a messageof section type 6 of an open-radio access network (O-RAN), and thesecond control message comprises the channel information.

In some embodiments, the at least one processor is configured totransmit a management message related to the section extension field,and the management message is configured in a management plane.

In some embodiments, the regularization parameter is used to calculate abeamforming weight for a minimum mean square error (MMSE) operation, andthe regularization parameter corresponds to a regularizationFactor fieldof a message of section type 6 of an open-radio access network (O-RAN).

According to embodiments, a device of a radio unit (RU) of a basestation in a wireless communication system, the device comprises atleast one transceiver; and at least one processor coupled to the atleast one transceiver, wherein the at least one processor is configuredto: receive a first control message comprising a section extension fieldfrom a digital unit (DU) via a fronthaul interface; identify aregularization parameter based on the section extension field; andacquire a beamforming weight based on the regularization parameter,wherein the first control message is configured to schedule a terminalin a control plane.

In some embodiments, additional information comprises the regularizationparameter.

In some embodiments, the first control message corresponds to a controlmessage of section type 5 of an open-radio access network (O-RAN), andthe first control message comprises scheduling information on theterminal.

In some embodiments, the at least one processor is further configured toreceive a management message related to the section extension field, andthe management message is configured in a management plane.

In some embodiments, the at least one processor is configured to:receive a management message related to the regularization parameter,which is configured in a management plane, from the DU; based on themanagement message, identify, as a scheme of transferring theregularization parameter, at least one scheme of a scheme via the firstcontrol message or a scheme via a second control message configured toperiodically transmit channel information in the control plane; receivethe second control message comprising another regularization parameterfrom the DU; identify one of the regularization parameter or the otherregularization parameter according to the at least one scheme; andacquire the beamforming weight based on the identified one of theregularization parameter or the other regularization parameter.

In some embodiments, the second control message corresponds to a messageof section type 6 of an open-radio access network (O-RAN), and thesecond control message comprises the channel information.

In some embodiments, the regularization parameter is used to calculatethe beamforming weight for minimum mean square error (MMSE) operation,and the regularization parameter corresponds to a regularizationFactorfield of a message of section type 6 of an open-radio access network(O-RAN).

In some embodiments, the beamforming weight is calculated based onchannel matrix, the regularization parameter, and a power normalizedparameter for limiting full power.

In some embodiments, to calculate the beamforming weight, the at leastone processor is further configured to: generate a channel covariancematrix for interference/noise based on a channel matrix and theregularization parameter, and determine a beamforming weight matrixbased on the channel covariance matrix.

Methods disclosed in the claims and/or methods according to variousembodiments described in the specification of the disclosure may beimplemented by hardware, software, or a combination of hardware andsoftware.

When the methods are implemented by software, a computer-readablestorage medium for storing one or more programs (software modules) maybe provided. The one or more programs stored in the computer-readablestorage medium may be configured for execution by one or more processorswithin the electronic device. The at least one program may includeinstructions that cause the electronic device to perform the methodsaccording to various embodiments of the disclosure as defined by theappended claims and/or disclosed herein.

The programs (software modules or software) may be stored innon-volatile memories including a random access memory and a flashmemory, a read only memory (ROM), an electrically erasable programmableread only memory (EEPROM), a magnetic disc storage device, a compactdisc-ROM (CD-ROM), digital versatile discs (DVDs), or other type opticalstorage devices, or a magnetic cassette. Alternatively, any combinationof some or all of them may form a memory in which the program is stored.Further, a plurality of such memories may be included in the electronicdevice.

In addition, the programs may be stored in an attachable storage devicewhich may access the electronic device through communication networkssuch as the Internet, Intranet, Local Area Network (LAN), Wide LAN(WLAN), and Storage Area Network (SAN) or a combination thereof. Such astorage device may access the electronic device via an external port.Further, a separate storage device on the communication network mayaccess a portable electronic device.

In the above-described detailed embodiments of the disclosure, anelement included in the disclosure is expressed in the singular or theplural according to presented detailed embodiments. However, thesingular form or plural form is selected appropriately to the presentedsituation for the convenience of description, and the disclosure is notlimited by elements expressed in the singular or the plural. Therefore,either an element expressed in the plural may also include a singleelement or an element expressed in the singular may also includemultiple elements.

While the disclosure has been shown and described with reference tovarious embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the disclosure as definedby the appended claims and their equivalents.

What is claimed is:
 1. A method performed by a distributed unit (DU) ofa base station in a wireless communication system, the methodcomprising: based on a capability of a radio unit (RU), transmitting, tothe RU, a management plane message associated with a regularizationfactor in a section type 5 for user equipment (UE) schedulinginformation, wherein the regularization factor is used for minimum meanssquare error (MMSE) calculation of generating multi-user (MU)beamforming weight for UEs in a slot.
 2. The method of claim 1, whereinthe section type 5 is defined in an open-radio access network (O-RAN).3. The method of claim 1, further comprising: generating a control planemessage using the section type 5 for the UE scheduling information,wherein the control plane message includes section extension informationindicating the regularization factor, and transmitting, to the RU, thecontrol plane message.
 4. The method of claim 1, wherein theregularization factor is associated with a noise variance used for theMMSE calculation.
 5. The method of claim 1, wherein the regularizationfactor is transmitted to the RU from the DU instead of a section type 6for channel information.
 6. The method of claim 3, wherein the sectionextension information includes: information of a type of the sectionextension information, the type associated with the regularizationfactor, and information of a length of the section extensioninformation, and wherein a length of the regularization factor is 16bits.
 7. The method of claim 1, wherein a value of the management planemessage indicates that the regularization factor is transmitted in thesection extension information of the section type 5 or theregularization factor is transmitted in another section type.
 8. Amethod performed by a radio unit (RU) of a base station in a wirelesscommunication system, the method comprising: based on a capability ofthe RU, receiving, from a distributed unit (DU), a management planemessage associated with a regularization factor in a section type 5 foruser equipment (UE) scheduling information, wherein the regularizationfactor is used for minimum means square error (MMSE) calculation ofgenerating multi-user (MU) beamforming weight for UEs in a slot.
 9. Themethod of claim 8, wherein the section type 5 is defined in anopen-radio access network (O-RAN).
 10. The method of claim 8, furthercomprising: receiving, from the DU, a control plane message includingsection type 5 for the UE scheduling information, wherein the controlplane message includes section extension information indicating theregularization factor; identifying the regularization factor from thesection extension information; and acquiring a beamforming weight basedon the regularization factor.
 11. The method of claim 8, wherein theregularization factor is associated with a noise variance used for theMMSE calculation.
 12. The method of claim 8, wherein the regularizationfactor is received from the DU instead of a section type 6 for channelinformation.
 13. The method of claim 10, wherein the section extensioninformation includes: information of a type of the section extensioninformation, the type associated with the regularization factor, andinformation of a length of the section extension information, andwherein a length of the regularization factor is 16 bits.
 14. The methodof claim 8, wherein a value of the management plane message indicatesthat the regularization factor is included in the section extensioninformation of the section type 5 or the regularization factor isincluded in another section type.
 15. A device of a distributed unit(DU) of a base station in a wireless communication system, the devicecomprising: at least one transceiver; and at least one processor coupledto the at least one transceiver, wherein the at least one processor isconfigured to: based on a capability of a radio unit (RU, transmit, tothe RU, a management plane message associated with a regularizationfactor in a section type 5 for user equipment (UE) schedulinginformation, and wherein the regularization factor is used for minimummeans square error (MMSE) calculation of generating multi-user (MU)beamforming weight for UEs in a slot.
 16. The device of claim 15,wherein the section type 5 is defined in an open-radio access network(O-RAN).
 17. The device of claim 15, wherein the at least one processoris further configured to: generate a control plane message using thesection type 5 for the UE scheduling information, wherein the controlplane message includes section extension information indicating theregularization factor in the section extension information, andtransmit, to the RU, the control plane message.
 18. The device of claim15, wherein the regularization factor is associated with a noisevariance used for the MMSE calculation.
 19. The device of claim 15,wherein the regularization factor is transmitted to the RU from the DUinstead of a section type 6 for channel information.
 20. The device ofclaim 17, wherein the section extension information includes:information of a type of the section extension information, the typeassociated with the regularization factor, and information of a lengthof the section extension information, and wherein a length of theregularization factor is 16 bits.
 21. The device of claim 15, wherein avalue of the management plane message indicates that the regularizationfactor is transmitted in the section extension information of thesection type 5 or the regularization factor is transmitted in anothersection type.
 22. A device of a radio unit (RU) of a base station in awireless communication system, the device comprising: at least onetransceiver; and at least one processor coupled to the at least onetransceiver, wherein the at least one processor is configured to: basedon a capability of the RU, receive, from a distributed unit (DU), amanagement plane message associated with a regularization factor in asection type 5 for user equipment (UE) scheduling information, andwherein the regularization factor is used for minimum means square error(MMSE) calculation of generating multi-user (MU) beamforming weight forUEs in a slot.
 23. The device of claim 22, wherein the section type 5 isdefined in an open-radio access network (O-RAN).
 24. The device of claim22, wherein the at least one processor is further configured to:receive, from the DU, a control plane message including section type 5for the UE scheduling information, wherein the control plane messageincludes section extension information indicating the regularizationfactor, identify the regularization factor from the section extensioninformation, and acquire a beamforming weight based on theregularization factor.
 25. The device of claim 22, wherein theregularization factor is associated with a noise variance used for theMMSE calculation.
 26. The device of claim 22, wherein the regularizationfactor is received from the DU instead of a section type 6 for channelinformation.
 27. The device of claim 24, wherein the section extensioninformation includes: information of a type of the section extensioninformation, the type associated with the regularization factor, andinformation of a length of the section extension information, andwherein a length of the regularization factor is 16 bits.
 28. The deviceof claim 22, wherein a value of the management plane message indicatesthat the regularization factor is included in the section extensioninformation of the section type 5 or the regularization factor isincluded in another section type.